Parallel
Exodus 15:23
Swete's Septuagint · Berean Standard Bible
ἮλΘον δὲ εἰς Μερρά καὶ οὐκ ἠδύναντο πιεῖν ἐκ Μέρρας, πικρὸν γὰρ ἢν· διὰ τοῦτο ἐπωνόμασεν τὸ ὄνομα τοῦ τόπου ἐκείνου πικρία.
And when they came to Marah (note: Marah means bitter.), they could not drink the water there because it was bitter. (That is why it was named Marah.)